src/firmware/gigaboot/lib/bootbyte.c

// Copyright 2022 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "bootbyte.h"

#include <stdint.h>
#include <zircon/boot/image.h>
#include <zircon/compiler.h>

#include <efi/runtime-services.h>

char16_t kBootbyteVariableName[] = ZIRCON_BOOTBYTE_EFIVAR;
efi_guid kZirconVendorGuid = ZIRCON_VENDOR_GUID;

efi_status get_bootbyte(efi_runtime_services* runtime, uint8_t* bootbyte) {
  size_t size = sizeof(*bootbyte);
  efi_status status = runtime->GetVariable((char16_t*)kBootbyteVariableName, &kZirconVendorGuid,
                                           NULL, &size, bootbyte);
  if (size != sizeof(*bootbyte)) {
    return EFI_BUFFER_TOO_SMALL;
  }
  return status;
}

efi_status set_bootbyte(efi_runtime_services* runtime, uint8_t bootbyte) {
  return runtime->SetVariable((char16_t*)kBootbyteVariableName, &kZirconVendorGuid,
                              ZIRCON_BOOTBYTE_EFIATTR, sizeof(bootbyte), &bootbyte);
}